Door closer



April 8, 1953 M. KALTHOFF 2,636,210

DOOR CLOSER Filedbec. 27, 1950 s Sheets-Sheet 1 A TTORNE YS April 8,- 1953 M. KALTHOFF 2,636,210

DOOR CLOSER Filed Dec. 27, 19st; 5 Sheets-Sheet 2 M k INVENTOR. ii gil mfim ATTOR/WFYS I April 28, 1953 M. KALTHOFF 2,636,210

DOOR CLOSER Filed Dec. 27, 1950 3 Sheets-Sheet 3 IN VEN TOR.

Patented Apr. 28, 1953 UNITED STATES PATENT OFFICE DOOR CLOSER Max Kalthoff, Glenbrook, Conn.

Application December 27, 1950, Serial No. 202,961. a

14 Claims.

This inventionrelates to door closers of the type, in which a spring, wound up when the door is opened, closes the door, and the closing action is regulated by forcing fluid at a controlled rate from one side of a piston within a cylinder to. the other. More particularly, the invention is concerned with a novel door closer, which is adapted for use on either a right-hand or a lefthand door, the conversion from one use to the other requiring only simple changes, which can be easily made. The new closer is similar to that disclosed in my co-pending application, Serial No. 66,749, filed December 22, 1948, now Patent 2,537,059, issued January 9, 19 51, but differs from the prior closer in thatit is simpler in construction andthus less expensive to produce. At the same time, the new closer affords all the advantages of the prior closer.

In its simplest form, the new closer comprises a cylinder for fluid containing a piston and having an outer tubular member extending upwardly from its top. A shaft extends axially through the cylinder and member and has an axial bore lying within the cylinder and connected to the interior of the cylinder through ports near the ends of the latter. The piston loosely encircles the shaft and has a passage connecting opposite faces of the piston and a check valve permitting downward flow only through the passage. The piston and shaft are connected by a threaded connection and means are provided for permitting the piston to move lengthwise of the cylinder, while preventing angular movement of the piston relative to the cylinder. An inner tubular member encircles the shaft within the outer tubular member and a spring lies between the members and has its ends secured to respective members. An operating arm is secured to the shaft and sleeve and is connected to the door in the usual way, the cylinder and Outer tubular member being then secured to the door frame. When the door is opened, the shaft is rotated to raise the piston and 'wind up the spring, the fluid flowing through the pistonto the lower side thereof. When the door is. re-v leased, the spring rotates the shaftto swing the arm to close the door and this rotation of the shaft lowers the piston. The piston moving down forces the fluid through the lower port, the shaft bore, and. the upper port into the cyl inder above the piston, the rate of flow being controlled by a valve within the shaft bore and thus in turn determining the rate, at which the i c o d.

The new. loseri ncludes v u featu e 2 novelty, which will be made clear in the following detailed description, which is to be .read in connection with the accompanying drawings. In the drawings,

5 Fig. 1 is an exploded perspective view, with parts broken away, of the upper part of one form of the new door closer;

Fig. 2 is a top plan view, with parts broken away, of the closer of Fig. 1;

m I Fig. 3 is a vertical sectional view of the closer of Fig. 1;

Fig. 4 is a sectional view on an enlarged scale on the line 44 of Fig. 3;

Fig. 5 is a perspective sectional view of the flow control value;

Fig. 6 is a fragmentary view, partly in vertical section and partly in elevation, of the threaded connection between the shaft and piston;

Fig. '7 is a fragmentary plan view of the Diston check valve;

Fig. 8 is a view, partly inelevation and partly in vertical section, of a modified form of the closer;

Fig. 9 is a plan view of the closer of Fig. 8;

Fig. 10 is a diagrammatic horizontal sectional view, showing the. closer of Fig. 8 arranged for left-hand door operation;

Fig. 11 is a View, similar to Fig. 10 showing the closer of Fig. 8 arranged .for right-hand door 0 operation.

Fig. 12 is a view, partly in elevation and partly in section, of a modified form of the closer of Fig. 8;

Figs. 13 and 14 are diagrammatic views showing the mode of operationof a form of the new closer for use on a right-hand door;

Fig. 15 is a view,.partly in top plan and partly I in horizontal section, of the new closer .in operation on a right-hand door;

Figs. 16 and 17 are. diagrammatic views showing the mode of operation of a form. of the new closer for use on a left-hand door; and Fig. 18 is a view, partly in top plan and partly in horizontal section, of the new closer .in operation on a left-hand door.

The new closer, in the form shown in Figs. 1-7, inclusive, comprises a housing 20, to which is attached a bracket 2| for mounting the closer on the face of adoor near. its upper .end. A

- cylinder 2Zis disposed within .the housing and is closedat its lower end by a cap 23 threaded in place. The cap has. a central bOSs 23a extending downwardly through a central opening through the lower end of the housing and the boss terminates in an externally threaded. neck 2%. vis mounted for rotation in the bearings.

advance it lengthwiseof. the: bore.

23b, on which is mounted an internally threaded sleeve 24 projecting beyond the neck. The central portion of the cap and the upper end of boss 2311 are bored to form a step bearing for the lower end of a shaft 25, which extends axially through the cylinder and out of the top of housing 20.

An outer tubular member 26, formed as an integral extension from the closed top 22a of cylinder 22, extends upwardly nearly to the top of housing and is partially closed at its upper end by a cap 21 screwed over the end of the extension and held in place by a-screw 28 threaded through the cap and entering a slot in the upper edge of member 26. A central post 29, integral with the top 22a of the cylinder, extends upwardly through the member 26 and terminates flush with the outer surface of cap 21. The post 29 is axially bored to form upper and lower bearings separated by a chamber Shaft extends through the bore and The shaft is encircled above the upper bearing by packing held in place by a gland nut 30 threaded into the upper end of the bore. inclined passages 22b lead through the top 22a of cylinder 22 into the chamber 29a within post 29. An inner tubular.member 3| encloses the post and, at its lower end, lies in contact with the upper surface of top 220; of the cylinder. At its upper end, the member 31 is provided with a flange containing a series of openings em.

The outer tubular member 26 is longitudinally slotted at 32 and the inner tubular member 3| is similarly slotted at 33. A flat spiralspring 34 lies between the tubular members with its ends received in the respective slots. The external diameter of the tubular member 26 is less than the internal diameter of the adjacent part of the housing 20 and the member and housing are separated by a spacer ring 35 seated on a circumferential shoulder on the outer surface of member '26.

The shaft 25 has'an axial bore 36 extending upward from its'lower end and the bore is connected to the interiorof cylinder 22 by an upper port 31 near the top of the cylinder, a middle port 38 about midway of the cylinder, and a lower port 39 just above cap 23 closing the lower end of the cylinder. A control valve assembly, comprising a stem 40 and spaced plugs 41, 42 mounted thereon, lies within bore 36- in the shaft. The plugs fit the bore snugly and each plug is formed with a series of lengthwise passages 4la, 42a, respectively. The stem II] is threaded near its lower end and passes through a threaded opening through boss 23a. 'Within neck 23?), the stem is encircled by packing 43'- held in place by a gland nut 44, which is threaded into the neck. The end of the stem is exposed within sleeve 24 and is provided with a knurled disk 45, by which 'the'stem may be rotated to The position of the plugs 4|, 42 on the stem 40 is such that, by rotation of stem 40, port 31 may be opened to the desired extent, while port 38-remains either open or closed.

A piston 46 lies within cylinder 22 and has a skirt formed with longitudinal slots 46a receiving rollers 41 mounted within the cylinder on studs 48 extending through the wall of the cylinder in diametrical relation; The piston'has a central hub 49, which projects upwardly .from its head and is internally threaded-to cooperate with a threaded enlargement 50 on shaft 35.

A pair of Preferably, the enlargement and boss are provided with a multiple thread and one convolution is omitted to provide a space for port 33 through the enlargement. The web of the piston connecting its skirt and hub 69 is formed with a plurality of openings 5| and a fiat ring 52 is mounted below the web between the skirt and hub on rods 53 extending between the skirt and hub. Below each opening 51, the opposed walls of the skirt and hub of the piston are cut away to form passages 5|a, 5lb past the inner and outer edges of ring 52. When the closer is to be used, a quantity of fluid, such as oil, is introduced into the cylinder to a level above the piston when the latter is in its lowermost position. When the piston is raised in the cylinder, the fluid passes freely through openings 5! and passages 5m, 5|b past ring 52 to the bottom of the cylinder. Upon downward movement of the piston, the ring 52 is held against the lower surface of the web of the piston and closes openings 5!. The openings and ring thus form a check valve permitting the fluid to pass downwardly through the piston but preventing its upward movement.

The bracket 2| i's provided with a stop Zia, which is secured to housing 20 and projects upwardly above the top of the housing, and a block 54 secured to the top of cap 2? normally lies in engagement with one side of the stop. The block is provided with a threaded opening 54:! for a purpose to be described. An arm 55 is mounted to encircle the end of shaft 25 pro jecting above the top of the housing and the arm is connected to the shaft against rotation. For this purpose, the shaft may have a flat, indicated at 25c, and the opening in the arm, through which the shaft projects, may be formed with a similarflat surface. Arm 55 extends beyond the edge of the housing and normally cooperates with the other side of stop 21a. The arm is connected by a pin 56 to the flange of the inner tubular member 3|, the pin being receivable in one of the openings 3la in the flange of the member.

Arm 55 has a tubular extension 55a encircling shaft 25 above the arm, and an operating arm 57 is mounted on the extension 55 for free r0- tation. Shaft 25 has a threaded end section 251) projecting beyond extension 55a and the operating arm 51 is held in place by a nut 58 threaded on the end of the shaft and engaging --a washer 58a resting on top of the operating arm. At one end, the operating arm has a ball 5111, by which the arm can be connected through a link 59 to a bracket 60 on the frame 5! of the door. At its other end, arm 51 has a short portion 5127 having an opening for a pin 52, which may be threaded into opening 54a of block 52, or into an opening 55b in arm 55 adjacent its outer end.

In the preliminary adjustment of the closer, the spring 34 is tightened to the initial extent by means of a tool inserted in a pair of openings 3la in the flange of the inner-tubular member 3| and then employed to rotate the tubular member and wind up the spring. When the spring istightened, pin 56 is passed through the opening in arm 55 and into one of the openings am. When the door is closed, the reaction of the spring holds the block 54 in contact with one edge of stop2la and arm 55 in contact with the other edge.

. When the closer is to be used on a right-hand door, that is, a door'which, when opening toward 'th'e' observer, has its knob at'the right side; i the operating arm is connected by pin 62' toblock 54.

When the door is opened (Fig. ),:the operating arm moves counter-clockwise'and;be-

' cause of its connection through block 54 to cap spring tends to hold arm 55 in contact with stop 2|a and shaft does not rotate. The rotation of the cylinder 22 causes piston 46 to rotate with it, because of the engagement of rolls 4'! in slots 46a in the skirt of the piston. As the piston rotates, its threaded engagement with the enlargement 50 on shaft 25 cause the piston to rise within the cylinder. As a result, the fluid within the cylinder flows downwardly through openings 5| and past ring 52 into the bottom of the cylinder.

When the opened door is released, the spring acts to restore the cylinder assembly to its original position and the piston begins to move down the shaft. When the piston is in its uppermost position, it closes port 38 and opens port 39. Accordingly, when the piston moves down, it forces the fluid beneath it through port 39 and up through the bore in shaft 25 through port 31 into the cylinder above the piston. The fluid ordinarily used is oil and, in the operation of the closer, some of the oil from the space above the piston passes through passages 221) into chamber 29a. and lubricates the shaft 25. The rate of flow of the fluid through the bore in the shaft determines the speed, with which the piston moves down, and thus, the speed, at which the door closes. The rate of flow through the shaft bore is controllable by the position of plugs 4|, 42 within the bore, as follows.

If it is desired that the door close with a steady V movement, stem 40 is threaded into neck 23b,

until plug 42 closes port 38 and plug 4| leaves port 31 open to the desired degree to give the door the speed of closing movement preferred.

With this adjustment of the parts, the fluiddisplaced by the downward movement of the piston passes through port 39 into the bore in shaft 25 and through passages 42a in plug 42 and thence beneath plug 4| through port 31 into the cylinder. If it is desired that the door closeslowly for most of its closing movement and then close more rapidly for the last part of the movement to insure that the door will be latched, stem 40 is backed out of nut 44 to move plug 4| downwardly partially past port 31. justment of the stem, plug 42 lies wholly below port 38. Accordingly, as the piston begins to move down, port 3'| is open at all times,.so that fluid can pass through the port from the bore into the cylinder above the piston. Justbefore the piston reaches the lower end of its travel, it uncovers port 38 and, in the remainder of the downward movement of the piston,.the fluid may escape from the bore in shaft 25 through both ports 3'! and 38. As a result, the lastpart of the downward movement of the piston is rapid and the door closes with a quick movement.

If the new closer is to be mounted on a lefthand door (Fig. 18), the operating arm 51 is connected by its pin 62 to arm 55 and through pin 56 to the inner tubular member 3l. Also, the operating arm is connected to shaft 25, since arm 55 is secured to the shaft against rotation. When the door is opened, the operating arm, is

. movedclockwise and this causes rotation of the With this ad- :sh'aft, which acts througlrithethreaded "connection'to "raise the pistonwithin the cylinderpg During such action, the blocke54-vremainswin contact with one side of'stop 2112:: ii if? Ifan attemptis made-to-shut an open door equipped withthe closermo're rapidly than its normal rate, the following action takes place.

1- Assuming that the door'is of the left-hand type, the opening of the door causes'the operating arm to move clockwise and arm' to wmove away from stop 2|a. When the door isreleased; the

.spring begins to rotate the innertubular member, shaft 25, arm 55, andoperating'arm' 51 in a counter clockwise direction; If, "at: this time, additional force is applied to the door, theresistance to flow'offluid from beneath the'piston upward through the bore'in shaft 25 and into 'cylinder 22 through port '31 preventslthe piston from being moved "downwardly more rapidly than its normal rate; The'additional force then causes a counter-clockwise rota'tionofthe cylinder assembly and, in' such movement, "therollers"4'| act on the walls of slots 46a in the skirt of the piston and tend to cause the piston to rotate counter-clockwise! The piston thus rotates in the same direction as shaft 25 and does notmove downwardly through thecylinder at a me corresponding to that, at which the door is 'being closed. The counter-clockwisemovement of the cylinder assembly moves block 54.1.away from "stop 2|a and, as indicatdin Fig. 17, when the door is completely closed andbp'erating arm 51 is at rest, the spring? unw'inds" to produce a clockwise movement of the assembly. 'iThe 'piston then moves downwardly along shaft 25',-unti1 block 54 strikes stop" 2 |a.""-Thus, the application of additional closi'n'g' forceto the do'or does' not place any unduefstra'iri'upon the mechanism.

The form of the new closer shown in Figs.'1-7, inclusive, ma be employed 'onfeither a -righthand or a left-hand door, and the only adjustment required. is the connection of the operatin arm 51 by its pin 62 't'o' block 54 for :righthand operation and to arm 55 for left han'd operation. A simpler form of the closer is shown in Figs. 8+11, inclusive, and this form of the closermay also be employed for either right-hand or lefthand operation but requires adjustment and replacement of parts. 7, 3 The closer shown in Figs; 8- 11; inclusive is V closely similar to that shown'm Fi s; 1-7;, inclusive but includes no housingsimilar to housing 20. Instead, the bracket l i3jfor attaching the V closer to a door is connectedto an outertubular me mber 64 corresponding to member "26; and formed as an integral upwardextensibn from cylinder 65 containing apiston similar to piston .D li der, 65 w th the; b mbe bu ar m mber hem- 956 end of a valve assembly lying within albore in sh'aftlil and identical withthe assembly, consisting of stem 40 and p1eg's-'-4 |,s2. 7 The outer tubular-member 64 is" closed atits'upper'end by a cap. 10 and-a hollow p'ost"H prOiectingupwardly within member 64 from the closedtop 55a of the cylinder. encloses shaft-B'I... The piston is formed with a chamber 1 a;-encircling. shafttl, and lubricating passagestfib connect the interior n.dthasi a lo i d s .2 receivin o da fi' prine ausea-21o The shaft 61 projects above the as of the cap 10 and the inner tubular member 12, and the exposed portion of the shaft is provided witha fiat and terminates in a threaded end section 61a. An" arm M encircles the exposed portion of' the shaft and fits it tightly and the arm has an opening for a; pin 15 insertable into one. of a series of openings 12min a dance at the top of the inner tubular member 12". An operating arm 16; which is similar to arm 57, loosely encircles the shaft -1 above arm 16 and is secured in position by a nut 17a threaded on the end of the shaft and engaging a washer 11b encircling the threaded end of the shaft andlying against the top of arm 16. Arm 1B is connected to arm 34 by a pin 18"extending through an-opening in arm 16 and threaded into an opening in arm '14. projects beyond, the rim of the edge of cap '10 and bears against a stop 53a attached to bracket When the closer shown in Figs. 8-11, inclusive is to be used for left-hand operation, the spring is moved clockwisearm 16 will move away from stop 63a and the spring will be wound up. In this movement of the operating arm, the shaft 61 rotates clockwise and, because of its threaded connection with the piston, the piston rises within cylinder 65. The piston isof the same construction as piston 46 and the threaded connection is as shown in Fig. 3. The rising of the piston causes fluid to pass through it and, when the door is released and the spring begins to unwind, the shaft is rotated to move the piston downwardly and the fluid is forced through the bore of the shaft past the control valve assembly into the cylinder above the piston.

When the closer shown in Figs. 7-11, inclusive, is to be used for right-hand operation, the shaft 61 and the piston are replaced by a shaft and piston having a left-hand threaded connection. Also, spring [3, arm 14, and operating arm 16 are turned upside-down, so, that they have the relative positions shown in Fig. 11. When a door carrying the closer is opened, operating arm i5 and the shaft are turned counter-clockwise and thismovement causes the piston to rise within the cylinder in the usual way.

If it is desired to construct a closer, as shown in Figs. 8-11,; inclusive, for right-hand operation without employing a left-hand threaded connection between theshaft and piston, the construction shown in Fig. 12. may be used. In this form of the closer, the piston 19 has a hub 80, which is externally threaded and shaft BI is provided with an internally threaded sleeve 82 cooperating with the hub 80. The closer includes passages 83 for supplying lubricant to shaft 8|, these passages including inclinedportions similar to passages 22b and connecting portions in the top of sleeve 82 onthe shaft. The closer is otherwise of'the constructionshown in Figs. 8-11, inclusive.

The closer, in the form shown in Figs. 1-7, inclusive, has the advantage that no strain is placed on the mechanism in the event that an attempt is made to classes open door equipped with the closermore rapidly than its normal rate. Also, the closer may be converted from right-hand'to 1 left-handoperation and vice versa-by adjfit;

Arm 12 ment. sot-"parts; only. I The: closer, in the; form shown'in Figs. 8-11, hastheadvantage of being somewhat lighter in. weightand having fewer parts than'the first form described. Both forms of the closer make use of .a flat spiral spring and the same control valve assembly, which can be readily adjusted to vary the speed at which the door closes.

'the cylinder at opposite ends thereof, a piston within the cylinder encircling the shaft and having a passage. connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular'moveinent of the piston relative to the cylinder, while permitting thepis'ton to move lengthwise of the cylinder, said means including elements mounted on the inner wall of the cylinder and entering axial channels in the outer surface of the piston, an arm connected to the shaft and operable in one direction to rotate the shaft to raise the piston, and a spring opposing said rotational movement of the shaft.-

2. In a door closer, the combination of a vertical cylinder closedat its ends and containing a I fluid, a shaft extending axially through the cylinder to the lower end thereof and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior of the cylinder at opposite ends thereof, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting. the piston to move lengthwise of the cylinder, said means including elements mounted on the inner wall of the cylinder and entering axial channels in theouter surface of the piston, an arm connected to the shaft and operable in one direction to rotate the shaft to raise the piston, a spring opposing said rotational movement of the shaft, and a valve within the bore for controlling flow through the upper port.

3. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, a shaft extending axially through. the cylinder and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior of the cylinder, two of the ports lying at opposite ends of the cylinder and a third lying between said ends, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventng angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the cylinder, an arm connected to the shaft and oper- 4; In atdoo closer, the combination of a 'vertical cylinder closedat its ends andcntaining a fluid, a shaft extending axially-through the cylinder and having an axial boreextending the length of the cylinder and ports connecting the bore to the interior of the cylinder, two of the ports lying at opposite ends of the cylinder and a third lying between said ends, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting the piston to movelengthwise of the cylinder, an arm connected to the, shaft and operable in one direction to rotate the shaft to raise the piston, a spring opposing said rotational movement of the shaft, and a valve within the bore for controlling flow through the middle and upper ports, the piston uncovering the middle port as it nears the lower end of the cylinder.

5. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, an outer tubular member extending upwardly from the top of the cylinder, a shaft extending axially through the cylinder and memher and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior of the cylinder at opposite ends thereof, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the cylinder, an inner tubular member encircling the shaft within the outer tubular member, an arm connected to the shaft and operable to rotate the shaft to raise the piston, a spring encircling the shaft and lying between the tubular members, one end of the spring being connected to one member and the other end of the spring being connected to the other member, a stop, a pair of arms connected to the respective tubular members and engageable with opposite sides of the stop, and means for connecting the shaft operating arm to one of the tubular members.

6. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, a chamber on top of the cylinder, a shaft extendin axially through the cylinder and chamber and having an axial bore extending the length of the cylinder and ports connecting the bore, to the interior of the cylinder at opposite ends thereof, mean for holding the shaft against endwise movement, a piston within the cylinder encircling the shaft and having a-passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the cylinder, an arm connected to the shaft and operable in one direction to rotate the shaft to raise the piston, a spring encircling'the shaft within the chamber and opposing said rotational movement of the shaft, the spring having one end operatively connected to the shaft and the other end anchored to the wall of the chamber, and a stop normally engaged by a portion of said arm.

'7. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid,

a chamber on top of.the cylinder, a shaft extendingaxially through the cylinder and chamber and having an axial bore extending the length of the cylinder and ports connecting the boreto the interior of the cylinder at opposite ends thereof, means for holding the, shaft against endwise movement, a piston within the cylinder encircling the shaft and having a passageconnecting its opposite faces and a check valve permitting downward flow only. through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the cylinder, an arm connected to the shaft and operable in one direction to rotate the shaft to raise the piston, a sleeve encircling the shaft within the chamber and extending from the top of the cylinder to the top of the chamber, means connecting the sleeve to the arm, and a spring encircling the sleeve and having one end connected to the sleeve and the other to the wall of the chamber, the spring opposing said rotational movement of the'shaft by the arm.

8. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, a chamber on top of the cylinder, a shaft extending axially through the cylinder and chamber and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior 'of the cylinder at opposite ends thereof, means for holdin the shaft against endwise movement, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permittin downward flow only. through the passage, a threaded connection between thepiston and shaft,,means preventing angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the cylinder, an arm connected tothe shaft and operable in one direction to rotate the shaft to raisethe piston, a sleeve encircling the shaft within the chamber, a spring encircling the sleeve and having one end ,connected to the sleeve and the other to the wall of the chambenthe spring opposing said rotational movement of the-shaft by thej arm, a casing enclosing the cylinder and chamber and adapted to be secured to. the door frame, and means for operatively connecting the arm to one end of the p 9. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, a chamber on top of the cylinder, a shaft extending axially through the cylinder and chamber and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior of the cylinder at opposite ends thereof, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the cylinder, an arm eon nected to the shaft and operable in one direction to rotate the shaft to raise the piston, a sleeve encircling the shaft within the chamber, a spring encirclin the sleeve and having one end connected to the sleeve and the other to the wall of the chamber, the spring opposing said rotational movement of the shaft by the arm, a casing enclosing the cylinder and chamber and adapted to be secured to the door frame, a stop on the easing, arms attached to the sleeve and chamber,

respectivelyyand engageable with opposite sides of the stop, and means for operatively connecting the shaft operating arm to one end of the spring.

.'In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, a chamber on top of the cylinder, a shaft extending axially through the cylinder and chamber and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior of the cylinder at opposite ends thereof, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft, means preventing angular movement of the piston relativeto the cylinder, while permitting the piston to move lengthwise of the cylindena sleeve encircling the shaft within the chamber, the outer surface of the sleeve and the'inner surface of the chamber being longitudinally slotted, a spring encircling the shaft within the chamber and having its ends received in the slots in the sleeve and chamber wall, and an arm connected to the shaft and sleeve and operable to rotate the shaft to raise the piston, the spring opposing said rotational movement of the shaft.

11. In a door closer, the combination'of a vertical cylinder closed at its ends and containing a fluid, a chamber on top of the cylinder, a shaft extendin axially through the cylinder and chamber and having an axial bore extending the length of the cylinder and'ports connecting the bore to the interior of the cylinder at opposite ends thereof, means for holding the shaft against endwise movement, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, a threaded connection between the piston and shaft,'means preventing angular movement of the piston relative to the cylinder, While permitting the'piston to move lengthwise of the cylinder, a sleeve encircling the shaft within the chamber and extending'from the top of the'cylinder' to the top of the chamber, the outer surface of the sleeve and the inner surfaceof the chamber being longitudinally slotted, a spirally wound flat springencircling the shaft within the chamber and having its ends received in the slots in the sleeve and chamber wall, and an arm "connected to the shaft and sleeve and operable to rotate the shaft to raise the piston, the spring opposin said rotational movementof the shaft.

12. In a door closer, the combination of a vertical cylinder closed at its ends and containing a fluid, a chamber on top of the cylinder, a shaft extending axially through the cylinderand chamber and having an axial bore extending the length of the cylinder and ports connecting the bore to the interior of the cylinder at opposite ends thereof, a piston within the cylinder encircling the shaft and having a passage connecting its opposite faces and a check valve permittingdown- Ward flow only through the passage, a threaded 5 connection between the piston and shaft, means preventing angular movement of the piston relative to the cylinder, while permitting the piston to move lengthwise of the -'cylinder', a sleeve-encirclingthe shaft within the chamber; the outer surface of the sleeveand the inner surface of the chamber being longitudinally slotted, a springencircling the shaft within the chamber and having its ends received in the slots in the sleeve and chamber wall, a stop attached to the outer-surface of the chamber, an arm connected to thesleeve and engageable with thestop, and an operating arm connected to the shaft and the first armand operable torotate the shaft to raisethe piston, the spring being wound 'up during suchmovement of the operating arm and shaft.

13. In a door closer, the combination of averticalcylinder closed-at its end' a'nd containing a fluid, a shaft extending axiallythrough the cylinder and having anaxialfib'ore extending the length of the cylinder and ports connectingthe bore to the interior "of the cylinder-at opposite ends thereof, a piston within the cylinder en'- circling the shaft and having apassage connecting its opposite facesand a check valve permitting downward flow only through I thepassage," a threaded connection between the piston and shaft, means preventing angular movement of the piston to move lengthwise of the cylinder, an arm 'connected to the shaftand operable inone dire'cti'on to rotate the shaft to raise the piston,- a spring opposing said rotational-movementof the shaft, and a valve within the bor'e'for controlling now through the upper port, the valve havinganoperating stem projecting out of the lower end of'the bore and through the lower'end of the cylinder.

14. In a doorcloser, the combination of a -vertical cylinder closed at its endsa nd containing a fluid, a chamber on t'op'of'thecylincler; a shaft extending axially through the cylinder and chamber and having an axial bore extending the length of the cylinder and ports extending from the bore to the interior of the' cylinder at opposite ends thereof, a hollow post rigid with the cylinderand projecting upward from the top thereof within the chamber and-encircling the shaft therein, a piston within the cylinder having a passage connecting its opposite faces and a check valve permitting downward flow only through the passage, athreadecl connection between the piston and shaft, meanspreventing angular movementof the piston relative to thecylinder; while permitting thepiston to move lengthwise o'f the cylin'denan arm connected to the shaft-and operable to rotate the shaft to raise the piston, a sleeve onclosing the post Withinthe chamber and extending to the top of the chamber, a connection-between the arm and the sleeve, and a spring encircling the sleeve and having one end connected to the sleeve and-the other to the wall of the chamber, the spring opposingrotationalmovement of theshaft by the arm.

' lvIAX KALTHOFF.

- References Cited in the file of thispatent UNITED STATES PATENTS 

